Many structures, including buildings such as homes, offices, retail space, and manufacturing space, are built with at least a portion of the building in direct contact with soils. Soils provide a base or platform on which the building can rest, and that can serve to support the building. Soils can exhibit fluid characteristics, and as a consequence, a solid base such as a foundation, is generally provided as part of building construction. While a foundation may provide a more stable substructure than bare soil, the fluid properties of soils can compromise a foundation, or cause the foundation to weaken, degrade, or fail. Many different types of soils are encountered in different geographic locations and in different building situations, which can require adaptations so that the building foundation interacts with the soil in such a way as to provide adequate support and reduces, minimizes, or maintains relative movement of the building and the soil within acceptable tolerances.
FIG. 1A shows a cross-sectional view of a portion of a structure or house 10 that is built using slab on grade construction. Structure 10 can include footings 12 and stem walls 14 that together form foundation 16. Footings 12 can be made or concrete reinforced with steel, such as rebar. Stem walls 14 can similarly be reinforced concrete, or alternatively can be masonry or block. Together, foundation 16 can support a superstructure or a balance of structure 10 including walls 18 and a roof 20. Both walls 18 and roof 20 can be constructed of lumber. Alternatively, walls 16 can be constructed or masonry, block, steel, other metal, or any other suitable material.
Foundation 16 can be disposed in, and supported by, native soil 24. Soil 24 can also provide support for floor slab 26. Slab on grade construction includes a concrete floor slab 26 that can be poured, formed, or built within a perimeter formed by the stem wall 14. Floor slab 26 can be in contact, and often direct contact, with leveled or graded soil. The graded soil can be formed as a prepared pad of soil that has been compacted for stability and built to a particular elevation or grade to account for drainage away from the building and other issues. Advantageously, an intermediate layer of engineered soil or an aggregate base course (ABC) 28 including rock, sand, and dirt can be deposited, graded, wet, and compacted over native soil 24 before placing and finishing concrete floor slab 26 to reduce soil movement and attendant cracking of floor slab 26.
In other instances, foundation 16 may be disposed in, and supported by, native soil 24 while the floor is elevated above, and not in direct contact with, the soil 24. In such instances, an airgap or crawl space may be disposed or formed between the floor and the soil 24.
FIG. 1B shows a perspective view of a cross-section of a portion of the structure or house 10 that is built with the wall 18 coupled to, and resting on, the foundation 16. As shown in FIG. 1B the wall can comprise a horizontal base plate, sole plate, bottom plate, or mudsill 30. The base plate 30 may be made of wood, or metal, such as aluminum, steel (galvanized, stainless, or other), as well as any composite material or other suitable material. On top of the base plate 30, a number of vertical studs 32 are attached or coupled to the base plate 30 and the foundation 16. The studs 32 may be made of wood, or metal, such as aluminum, steel (galvanized, stainless, or other), as well as any composite material or other suitable material, that may be the same or different than base plate 30. The base plate 30 and the studs 32 may be attached or coupled to the foundation 16, and more particularly the stem wall 14, with multiple anchors, strap anchors, metal straps, or anchor bolts 34. The anchors 34 comprise a first portion 34a extending above and out of the stem wall 14 and a second or lower portion 34b encased in the stem wall 14 or coupled to the foundation 16. The first portion 34a of anchor 34 is coupled to the base plate 30, studs 32, or both, by mechanical fasteners 36 which comprise nails, screws, spikes, staples, or washers and bolts. The anchors 34 may comprise strap anchors 35a, as well as anchor bolts or j-bolts 35b, as shown in FIG. 1B. The j-bolts may couple the wall 18 to the stem wall 14 by including a lower portion of the j-bolt 35b disposed within cured concrete of the stem wall 14, and the upper portion of the j-bolt 35b being coupled to the base plat 30 with washer 35c and nut 35. A foam gasket 38 or other deformable material may be disposed between the base plate 30 and the stem wall 14 to close any gaps or spaces between the base plate 30 and the stem wall 14 to create a seal.